Along with other non-governmental organisations (NGOs), Aizhixing says it has recently come under increasing pressure from the government.
Its workers complain of arbitrary police searches, new bureaucratic hurdles and general official interference.
Aizhixing’s founder, Aids activist Wan Yanhai, was so worried about his own safety that he fled to the United States with his wife and four-year-old daughter.
He said the government had launched a “war” on civil society in China, limiting the activities of any organisation not controlled by its officials.
It is a charge the government has declined to comment on. The Ministry of Civil Affairs did not want to talk to the BBC about the issue.